The Oki Islands are a World Geopark archipelago in the Sea of Japan, warmed by the Tsushima Current and seldom on a diver's list, though Japanese night diving began here. Boats from Nishinoshima visit linked sea caves at Yabashiri Nijurokketsu, the walls of Hoshi-no-kami-shima and an inner-sea point where yellowtail and amberjack chase schools of horse mackerel and blackfish, while Dōgo adds the lone rock of Oki no Tatami. Expect rock, weed and sand with plenty of small life.
About diving in Oki Islands
Diving on Nishinoshima is day-boat work from the harbour, with the closest point about 10 minutes out and Hoshi-no-kami-shima 30 minutes away. Dive staff meet arriving ferries at Beppu port. At Iguri the boat anchors between two rocks and the dive starts with a descent to about 16 m. Sites are chosen on the day to suit each diver's skills and the sea conditions. On Dōgo a separate service runs morning and afternoon dive sessions alongside sea kayaking.
This is Sea of Japan diving over volcanic rock, sponge-covered boulders, seaweed and sand. Shoals and pinnacles drop off to 25 m or deeper, sea caves riddle the coast, and where sand meets boulders jawfish peer out of the bottom. The weed and rock hide blennies, sponges and tiny critters. Over the top swim schools of chicken grunts, horse mackerel, blackfish and damselfish, and the islands have an endemic species of their own, the okimatsuge.
Most named points are graded for beginners, and the shallow caves at Katado and Hirashima let newer divers explore at an easy pace. The fast water at Nishigase and Hoshi-no-kami-shima belongs to experienced divers; the current carries nutrients that pull in schools of plankton-feeding fish. Macro photographers will find plenty to work on at Iguri, which looks plain at first glance, and at Oki no Tatami; both reward a slow search of the rock and weed.
Best time to dive Oki Islands
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Fair | Fair | Good | Good | Good | Prime | Prime | Prime | Fair | Fair | Good | Fair |
Diving runs all year. December to February is the rough stretch: high waves cancel ferries more often and the fast ferry stops in December, while the water bottoms out near 11 °C in March. Typhoon season runs from May to October. Early summer brings spawning bigfin reef squid, and from June to August the straits are calm, with visibility reaching 25 to 35 m. July averages 25 °C and August reaches 29 °C. September and October are the typhoon peak; autumn plankton dims the water but pulls in dense fish schools.
Dive types & marine life
Bigfin reef squid spawn at Katado in early summer, and banded houndsharks sometimes school there in autumn, when the current also brings fish from warmer southern waters. Yellowtail and yellowtail amberjack chase horse mackerel and blackfish at Kijigahana, and yellowtail schools swim into the current at Nishigase.
- Cave & cavern
- Wall
- Muck & macro
- Trevally & jacks
- Groupers
- Squid
- Reef fish swarms
- Macro critters
Best dive sites in Oki Islands
Uninhabited islet whose walls plunge into dark water
Reef
Two fused rocks where yellowfin amberjack swarm around the group
Yabashiri Nijurokketsu
Dives two caves of a coastal landmark where more than 26 sea caves link together.
Nishigase
Advanced point where a fast tide sweeps a drop-off falling past 30 m, with grunt schools.
Motoichiban
Submerged pinnacle topping out at 5 m, with good odds of meeting open-water fish.
Oki no Tatami
One huge rock off Dōgo, sitting on a carpet of white sand at 25 m.
Katado
Relatively shallow point with caverns to swim through.
Tōguri
Shoal that drops off as a wall to 25 m.
How to get to Oki Islands
Oki Airport on Dōgo has flights from Osaka Itami and Izumo. Oki Kisen runs up to three ferries a day from Shichirui and Sakaiminato on the mainland. Nishinoshima divers land at Beppu port, where the dive staff wait; the Dōgo dive service is 20 minutes by car from Saigō Port.
Photos from Oki Islands
Yuvalr · CC BY-SA 4.0
Questions divers ask
Can beginners dive the Oki Islands?+
Yes. Most Nishinoshima points are graded for beginners, including Yabashiri Nijurokketsu, whose wide caves are partly at the surface inside. Nishigase is rated advanced because of its fast tide.
Are dives on Dōgo guided in English?+
No. The Dōgo service runs its dive and sea-kayak sessions in Japanese only, and asks for a basic command of the language or previous scuba experience.
How should a dive trip plan around the weather?+
Watch the wind and wave forecasts before and during the stay. Typhoons occasionally hit the islands directly between May and October, and in winter strong northwesterly winds whip up rough seas; in both, the ferries stop and visitors can be stranded.
Sources
- Club Noah Oki — Club Noah Oki
- Club Noah Oki dive points — Club Noah Oki
- Club Noah Oki access — Club Noah Oki
- Diving and Sea Kayaking Experience (Oki no Kuni Diving) — Oki Islands Geopark Management Bureau
- Weather and Climate — Oki Islands Geopark Management Bureau
- Dive into the Other Oki Islands — Outdoor Japan
- Oki Islands — Wikipedia
- Oki Islands — Wikivoyage
- クラブノア隠岐 の紹介 — AQROS
- 隠岐 中ノ島・隠岐の島 島後のダイビング見どころ — Diver Online
- 水の中をめぐる旅【５】隠岐諸島・西ノ島 — note (hiisama)
- Sea water temperature in Okinoshima — SeaTemperatu.re
Photo credits
- Three small motorboats moored by a harbour wall, with a village and a green forested hill under grey cloud behind by Yuvalr, CC BY-SA 4.0, via Wikimedia Commons
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